The assembly of an automobile entails the attachment of multiple components to a core structure such as a unibody or a ladder-type frame. Many of the components are manufactured by one or more suppliers and then delivered to an original equipment manufacturer (“OEM”) for final assembly. The dimensions for each component that is to be attached to the automobile are specified by the OEM.
Because of limitations that are inherent in manufacturing processes and techniques, the actual dimensions of the component typically varies slightly from the dimensions that were specified for the component. For example, a molded plastic part will experience shrinkage as it cools. The shrinkage will impact the dimensions of the plastic part. The amount of shrinkage experienced by the plastic part will depend upon the time allotted for cooling, the temperature at which the plastic part cools, the precise formulation of the plastic materials used to mold the plastic part, and other factors. The cooling time, the cooling temperature, and the precise formulation of the plastic material cannot be controlled with absolute precision. Accordingly, unanticipated and unpredictable variations will arise in the amount of shrinkage experienced by a molded plastic part that will lead to variations in the dimensions of the component that is fabricated from the plastic part. The processes used to fabricate components from materials other than plastic also have limitations that will result in the component having dimensions that vary slightly from the specifications.
In recognition of this real-world circumstance, when specifying dimensions for components, the OEM will also specify a tolerance or acceptable deviation from the specified dimension. For example, when specifying that a component shall have a length of 100 cm, the OEM may also specify that the component will be acceptable if its length falls within 1.5 mm of 100 cm.
When components that deviate from their specified dimensions are attached to other components that also deviate from their specified dimensions, their respective dimensional deviations will be compounded. This is known as “stack up”. One consequence of stack up is that the attachment opening (an opening that is configured to receive a fastener) of one component may fail to align with the attachment opening of another component. In other words, instead of being concentric with one another, the attachment openings will be eccentric with respect to one another. When attachment openings of differing components are eccentric, the use of a standard fastener can cause one or both components to skew from its nominal position. In some cases, this skewing may have an aesthetically displeasing impact on the fit and finish of the components being joined, including the occurrence of gaps and/or buckling.
An earlier attempt to resolve this problem was disclosed in U.S. Pat. No. 3,367,383, issued to Neuschotz (hereinafter, “the '383 patent”). The '383 patent describes a fastener assembly that includes a threaded element carried by an outer body where the threaded element was free to move laterally with respect to the outer body. The outer body could be positioned concentrically within an attachment opening of a first component while the threaded element could be positioned concentrically within an attachment opening of a second component even though the two attachment openings were eccentrically oriented with respect to one another. Thus, the '383 patent's fastener permitted the components to be joined together without being skewed.
This solution, however, gives rise to a significant problem. The threaded element of the '383 patent's fastener is free to slide with respect to the outer body and therefore will be randomly and unpredictably positioned with respect to the outer body. As a result, the '383 patent's fasteners will be non-uniform (i.e., they will each have slightly different configurations). This, in turn, will introduce inefficiency into the process of assembling a vehicle. An assembly line worker seeking to insert the '383 patent's fastener into misaligned attachment openings will need to take additional time to visibly inspect or tactilely determine the location of the threaded element with respect to the outer body in order to accurately insert the threaded element into the misaligned attachment openings. This may render the '383 patent's fastener difficult and/or time consuming to use and, in extreme cases, may cause injuries to the hand and/or fingers of the assembly line worker.
Accordingly, it is desirable to provide an easy-to-use fastener that can join together two components having misaligned attachment openings. In addition, it is desirable to provide a method for use of such a fastener. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.